Why Building Geometry Matters by Allen Dusault

“In 1853 a rather eccentric gentleman named Orson Fowler published a book entitled, “The Gravel Wall and Octagon Mode of Building”. The book was a best seller of its day and it spurred a short-lived nationwide fad of building houses (and some barns) in an octagon shape, a radical idea then and now (he was also an early proponent of concrete in buildings which was a novelty in his day). It is estimated that 1,000 or so octagon houses were built across the country, a fair number of which are still standing. Although the book is all but forgotten its’ message is as relevant today as it was in the 1850s.

The central point of Fowler’s book is so logical and conceptually simple that even a fifth grader can understand its’ meaning, if not its implication. Briefly stated, an octagon is a more efficient shape than a square or a rectangle. The argument of course extends to the three dimensional form of these shapes. This is true both in terms of materials used to construct a building and the amount of volume that needs to be heated and cooled with approximately 25% more wall area for a rectangle than for an octagon. It is simple math – surface area to volume enclosed. Of course the shape doesn’t have to be an octagon – a hexagon, for example, is also more efficient than the ubiquitous rectangle.

Our love affair with the traditional rectangular shape for buildings means we pay added environmental and energy costs not once, but four times over the life of the structure. First, we pay in the construction phase – more building material means higher “embodied energy” in the building. That is a significant portion of the total lifecycle energy. We also pay for the added surface area with more fuel used to heat and cool a building than would be needed with less wasteful shapes. Greater exposed surface area also means greater maintenance and repair on the exterior (and potentially more damage from storms, hurricanes or tornadoes than a more efficient design). And finally, when the building comes to its end of life, more material must be torn down and hauled away. All that takes energy as well.

However, just because we are emotionally attached to our “plywood nostalgia box” homes doesn’t change physics. This is a critical environmental issue that won’t go away because it is “politically incorrect”. Surface area matters. The good news is our taste in building geometry is largely learned. And we can learn to appreciate new and different shapes, much like the shift in preference that developed for automobiles beginning with streamlining that occurred in the 1930s and 40s. But shifting our preferences in buildings shapes will require more than just waiting for a change in our preferences. A first step is to recognize the benefits of efficient geometries and then incorporate that into our sustainable building vernacular. And that could start a whole new wave of creativity.

When we think of green architecture, we need to start thinking outside the box.”

Read the full article at the source: iGreenBuild.com
Thanks to Cliff again for another good tip. Please send us your suggestions for new articles.


Comments

Is Green Architecture Missing a Footing? — 10 Comments

  1. There are strong cultural factors against geometric shapes like this. There’s enormous pressure to conform to what everyone else is doing. There are also major economic concerns such as resale value. You may never be able to sell a roundhouse, dome or octagonal house for instance. A house is often the largest investment people ever make. What if someone loses their job then gets another job in another city or state? They don’t want to be stuck with something not marketable. Also, homeowner associations and developers play a big role in creating generic looking neighborhoods.

  2. Buckminster Fuller had the same idea, and took it to it’s logical conclusion (how to build a sphere with the minimum of materials). The problem in both is actually wall space. It’s easier to fit our furniture in a box. Take a moment to look around the room you’re in right now. How much of your furniture is up against the wall? If the room was curved or trapezoidal, how much of your furniture would you need to change? How much would have to be custom made? (Less of an issue for octagonal than curved, but can still be an issue for cabinetry and large sofas.) Now, while some of us would see this a good excuse to pull out the carpentry tools and buy the heavy duty sewing machine for upholstery, for most people, how well their existing furniture fits into a new house is part of the evaluation process. So until you can go down to Lowe’s and pick up a curved couch or a 45 degree corner piece for the sectional, most people won’t go for a house that isn’t a box.

      • YES! that is a great house plan, Owen.

        We are dreaming of neighborhoods with octagonal homes for folks, helping to co create Regenerative Supportive Living.

        another great aspect of octagons is that you have eight walls where you can
        have windows/doors to look out.

        better cross flow of energy.

        the interior air circulates much better than in a box with corners.

        there are flat walls where you can add other octagon/s to enlarge the home space.

        many more reasons to come.

    • I live in a 28ft diameter Hogan–an eight sided strawbale home, traditional with the Navajo here. I LOVE it. There are two wings on it…entry and greenhouse on the S end, and bathroom on the W end. No problem whatsoever with furniture, though the kitchen wouldn’t lend itself to cookie cutter cabinets from Lowe’s…had to have a carpenter build it. And its is a super efficient and beautiful kitchen. I definitely prefer this shape to any other.

      • Octagonal is a good house shape for straw bales because they’re large rectangular blocks. The ideal is a wall length that matches an even number of bales perfectly. Ex: each side of the octagon has 5 bales. This way you don’t have to make custom sized bales.

        Gravel bags make a perfect foundation for the bales to raise them up off the ground so they don’t get water damaged. You can use scoria or pumice gravel in the gravel bags to create an insulated foundation.

        Adding a greenhouse on the south or southeast side as you’ve done is an excellent idea. In my plan I added lots of south facing windows and put plants on the windowsill.

        • The greenhouse wing actually on the East end with windows on both E and S sides (wing is square shaped) which works really well in Spring which is the only time I really use it. Then I have a sliding glass door on the S side of the main (octogonal) part of the house for direct winter heat gain. (Windows also in E, SW, NW sides. I love all the cheery light. I am not sure, Owen, if they planned for bale sizes when they built it.

          • Boy I am really having directional challenges today… the sliding glass door is facing SE, not direct S; But there is a big window to South. Maybe living in a house with eight sides DOES mess with your head sometimes! ☺

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